Dynamic power management in a portable media delivery system

ABSTRACT

A consumer electronic product (e.g., a portable media player ported to a media delivery accessory) is powered by a limited capacity DC power source (such as a battery or mini-fuel cell). The consumer electronic product limits the maximum allowable sound pressure level (SPL) that can be produced by the speakers. In one embodiment, the maximum allowable SPL is based upon an amount of stored energy available in the limited capacity DC power source.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of, and claims priorityunder 35 USC §121 to U.S. application Ser. No. 11/364,610 filed Feb. 27,2006 now U.S. Pat. No. 7,848,527.

FIELD OF INVENTION

This invention relates generally to personal, portable electronicdevices such as media players, radios and the like.

DESCRIPTION OF RELATED ART

Recent developments in consumer electronics have included theintroduction of portable media players (such as MP3 players, minidiskplayers), cell phones, personal digital assistants (PDAs) and the like.For example, in the case of an MP3 player (or, for that matter, anyother digital media playback device), a number of digitized audio filesare stored in a storage medium included in or coupled to the MP3 playerin a fashion deemed most suitable to the user. Until recently, thelistening enjoyment of these stored music files was typically limited tothe use of earphones or other individual listening devices preventingthe user from providing a listening experience to a group of devotees.In order to provide such a listening experience, a number of portableaccessories having comparatively large speakers have been developed.Such portable accessories are often known as speaker systems or speakerdocks. In any case, the portable accessories provide for broadcasting ofmusic to more than a single user. Unfortunately, however, the powerrequirements to drive the comparatively large speakers such as theportable accessory far outweigh the power requirement of the portablemedia player.

Therefore, there is a need for improved approaches to provide and managepower consumption and preserving overall power consumption of a consumerelectronic product by limiting power used to drive speakers.

SUMMARY OF THE INVENTION

A method for managing power in a media delivery system arranged tooutput audio by way of one or more speakers is described. A consumerelectronic product includes a portable media player arranged to playbacka selected one of a plurality of media files stored therein connected toa media delivery accessory unit having at least one speaker. When theconsumer electronic product is operating in a DC mode, a maximumallowable sound pressure level (SPL) of an output audio signal that canbe produced by the at least one speaker is set to a DC maximum allowableSPL.

In another embodiment, a consumer electronic product operable in a DCmode and an AC mode is described that includes a portable media playerarranged to playback a selected one of a plurality of media files storedtherein and a media delivery accessory unit electrically coupled to theportable media player having at least one speaker. When the consumerelectronic product is operating in the DC mode, a maximum allowablesound pressure level (SPL) of an output audio signal that can beproduced by the at least one speaker is set to a DC maximum allowableSPL.

In yet another embodiment, a method of shutting down a consumerelectronic product so as to avoid generation of audio artifacts isperformed by determining if a shutdown is imminent and muting an audioamplifier. A user feedback indicating that a loss of power is imminentis provided and if all remaining electronic components are not powereddown then all remaining electronic components in the consumer electronicproduct are shutdown. The user feedback is continued until all residualpower is exhausted.

Another embodiment provides computer program product executable by aprocessor for shutting down a consumer electronic product so as to avoidgeneration of audio artifacts. The computer program product includescomputer code for determining if a shutdown is imminent, computer codefor muting an audio amplifier; computer code for providing a userfeedback indicating that a loss of power is imminent, computer code forpowering down all remaining electronic components in the consumerelectronic product if all remaining electronic components are notpowered down, computer code for discontinuing the user feedback if allresidual power is exhausted, and computer readable medium for storingthe computer code.

Computer program product executable by a processor for shutting down aconsumer electronic product so as to avoid generation of audio artifactsis also described that includes computer code for determining if ashutdown is imminent, computer code for muting an audio amplifier,computer code for providing a user feedback indicating that a loss ofpower is imminent, computer code for powering down all remainingelectronic components in the consumer electronic product if allremaining electronic components are not powered down, computer code fordiscontinuing the user feedback if all residual power is exhausted, andcomputer readable medium for storing the computer code.

Other aspects and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by reference to the followingdescription taken in conjunction with the accompanying drawings.

FIG. 1 shows a media system in accordance with an embodiment of theinvention.

FIG. 2 shows a portable media player according to one embodiment of theinvention.

FIG. 3 shows a consumer electronic product in accordance with anembodiment of the invention.

FIGS. 4A-4B illustrates a monitored capacitor voltage and charge status,respectively, in accordance with an embodiment of the invention.

FIGS. 5-7 illustrate a speaker output for consumer electronic product inDC operating mode in accordance with an embodiment of the invention.

FIG. 8 shows a flowchart detailing a process in accordance with anembodiment of the invention.

FIG. 9 shows a flowchart detailing a process in accordance with anembodiment of the invention.

FIG. 10 shows a flowchart detailing a process in accordance with anembodiment of the invention.

FIG. 11 shows a flowchart detailing a process for shutting down theconsumer electronic product in accordance with an embodiment of theinvention.

FIG. 12 shows a representative schematic diagram of a charge statusmonitor in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made in detail to a particular embodiment of theinvention an example of which is illustrated in the accompanyingdrawings. While the invention will be described in conjunction with theparticular embodiment, it will be understood that it is not intended tolimit the invention to the described embodiment. To the contrary, it isintended to cover alternatives, modifications, and equivalents as may beincluded within the spirit and scope of the invention as defined by theappended claims.

A consumer electronic product in the form of a portable media deliverysystem is described. In particular, when the consumer electronic product(e.g., a portable media player connected to a media delivery accessoryhaving a plurality of speakers) is powered by a limited capacity DCpower source (such as a battery or mini-fuel cell), the consumerelectronic product limits the maximum allowable sound pressure level(SPL) that can be produced by the speakers. In one embodiment, thelimitation of the maximum allowable SPL is based upon an amount ofstored charge available in the limited capacity DC power source or insome cases an intermediate storage capacitor.

In the described embodiment, the media delivery accessory includes aprocessor, an audio output device, and limited capacity DC power sourcecoupled to an external power unit by way of a power cable. The portablemedia player is arranged to store any number and type of suitablyformatted digital multimedia data files that are ultimately selected bya user for playback. It should also be noted, that in a particularlyuseful embodiment, the media delivery accessory includes a userinterface that provides user input signals to the accessory. In thisway, the accessory performs a limited control function for the mediadelivery system by, for example, increasing or decreasing the soundvolume produced at a speaker unit coupled thereto.

The invention will now be described in terms of a consumer electronicproduct that includes a portable media player capable of storing anumber of multimedia digital data files connected to a media deliveryaccessory arranged to broadcast audio by way of a plurality of speakers.In the case of the media player being a pocket sized portable player(such as the IPOD™ player manufactured by the Apple Inc. of Cupertino,Calif.), the multimedia data files can include MP3 files as well as anyother appropriately formatted data files.

FIG. 1 is a diagram of a media system 100 according to one embodiment ofthe invention. The media system 100 includes a media delivery accessory102. The media delivery accessory 102 serves to output media, such asoutputting audio sounds. For example, the audio sound can pertain tomusic.

The media delivery accessory 102 includes a housing 104 that supports orcontains various components of the media delivery accessory 102. Thehousing 104 includes an opening or receptacle 106 and a connector 108disposed therein. Beyond the media delivery accessory 102, the mediasystem 100 also includes a portable media player 110. The portable mediaplayer 110 is, more generally, a portable computing device, such as themobile computing device 200 illustrated in FIG. 2. Although the portablemedia player 110 is fully operational apart from the media deliveryaccessory 102, the portable media player 110 can be connected to themedia delivery accessory 104. In particular, the portable media player110 includes a connector 112. The portable media player 110 can beplaced in the opening or receptacle 106 such that the connector 108physically and electrically connects with the connector 112 of theportable media player 110, thereby connecting the portable media player110 to the media delivery accessory 104. It should also be noted that insome cases the connection can be made wireles sly using a WiFi typewireless interface, for example.

The media delivery accessory 102 includes a plurality of speakers 118.In one embodiment, the speakers 118 include a pair of midrange speakersand a subwoofer speaker. The housing 104 also includes volume controldevices 120 and 122. In one embodiment, the volume control devices 120and 122 are buttons. Still further, the housing 104 can include anindicator light 124 that provide visual feedback to the user regardingthe operation or condition of the media delivery accessory 102. Thehousing 104 can also include a receiver window 126 that can be used by areceiver internal to the housing 104 when picking-up wirelesstransmissions from a remote controller 128 having a plurality of userinput controls 130. It should be noted that the remote controller 128can transmit any of a number of signals such as infrared, radiofrequency (RF), audio signals, and the like. Through use of the userinput controls 130 on the remote controller 128, the user is able toindirectly interact with the portable media player 110 or directlyinteract with the media delivery accessory 102. For example, the user ofthe remote controller 128 can interact with the user input controls 130to select a media item to be played on the portable media player 110with its audio output being provided by the speakers 118 of the mediadelivery accessory 102. The remote controller 128 can also be used toalter the volume of the audio output from the media delivery accessory102.

FIG. 2 shows a portable media player 200 according to one embodiment ofthe invention. The media player 200 is, for example, suitable for use asthe battery powered portable media player 110 shown in FIG. 1. The mediaplayer 200 includes a processor 202 that pertains to a microprocessor orcontroller for controlling the overall operation of the media player200. The media player 200 stores media data pertaining to media assetsin a file system 204 and a cache 206. The file system 204 is, typically,a storage disk or a plurality of disks. The file system 204 typicallyprovides high capacity storage capability for the media player 200.However, since the access time to the file system 204 is relativelyslow, the media player 200 can also include a cache 206. The cache 206is, for example, Random-Access Memory (RAM) provided by semiconductormemory. The relative access time to the cache 206 is substantiallyshorter than for the file system 204. However, the cache 206 does nothave the large storage capacity of the file system 204. Further, thefile system 204, when active, consumes more power than does the cache206. The power consumption is particularly important when the mediaplayer 200 is a portable media player that is powered by a battery (notshown). The media player 200 also includes a RAM 220 and a Read-OnlyMemory (ROM) 222. The ROM 222 can store programs, utilities or processesto be executed in a non-volatile manner. The RAM 220 provides volatiledata storage, such as for the cache 206.

The media player 200 also includes a user input device 208 that allows auser of the media player 200 to interact with the media player 200. Forexample, the user input device 208 can take a variety of forms, such asa button, keypad, dial, etc. Still further, the media player 200includes a display 210 (screen display) that can be controlled by theprocessor 202 to display information to the user. A data bus 224 canfacilitate data transfer between at least the file system 204, the cache206, and the processor 202. The media player 200 also includes a businterface 216 that couples to a data link 218. The data link 218 allowsthe media player 200 to couple to a host computer over a wiredconnection.

In one embodiment, the media player 200 serves to store a plurality ofmedia assets (e.g., songs) in the file system 204. When a user desiresto have the media player 200 play a particular media item, a list ofavailable media assets is displayed on the display 210. Then, using theuser input device 208, a user can select one of the available mediaassets. The processor 202, upon receiving a selection of a particularmedia item, supplies the media data (e.g., audio file) for theparticular media item to a coder/decoder (CODEC) 212. The CODEC 212 thenproduces analog output signals for a speaker 214. The speaker 214 can bea speaker internal to the media player 200 or external to the mediaplayer 200. For example, headphones or earphones that connect to themedia player 200 would be considered an external speaker.

The media player 200 also includes a wireless network interface 226arranged to wireles sly transmit any selected data from the media player200 to any appropriately configured receiver unit (e.g., the wirelessnetwork interface 114) over a wireless network. In the embodiment shownin FIG. 1, the wireless network interface 226 that takes the form of,for example, a “WiFi” interface according to the IEEE 802.11b or 802.11gstandards. Other wireless network standards could also be used, eitherin alternative to the identified standards or in addition to theidentified standards. Such other network standards could include theIEEE 802.11a standard or the Bluetooth standard.

In one embodiment, the media player 200 is a portable computing devicededicated to processing media such as audio. For example, the mediaplayer 200 can be a media player (e.g., MP3 player), a game player, aremote controller, a portable communication device, and the like. Thesedevices are generally battery-operated and highly portable so as toallow a user to listen to music, play games or video, record video ortake pictures, communicate with others, and/or control other devices. Inone implementation, the media player 200 is a handheld device that issized for placement into a pocket or hand of the user. By beinghandheld, the media player 200 is relatively small and easily handledand utilized by its user. By being pocket sized, the user does not haveto directly carry the device and therefore the device can be takenalmost anywhere the user travels (e.g., the user is not limited bycarrying a large, bulky and often heavy device, as in a portablecomputer). Furthermore, the device may be operated by the user's hands,no reference surface such as a desktop is needed.

FIG. 3 shows a consumer electronic product 300 in accordance with anembodiment of the invention. In the described embodiment, the consumerelectronic product 300 is formed when the portable media player 110 isplaced in the opening of receptacle 106 such that the connector 108physically and electrically connects with the connector 112 of theportable media player 110 thereby creating a data/power pathway betweenthe portable media player 110 and the media delivery accessory 102. Themedia player 102 includes a media player internal power supply 302arranged to store energy used to power to media player 110 before (i.e.,booting up) and during playback of selected digital media files. Themedia player 110 also includes a memory unit 304 suitably arranged tostore, in addition to media files, media player operational parameters306 indicative of an operating state of the media player 110. Forexample, the media player operational parameters 306 can include anindication of whether or not a backlight used to illuminate the display114 is operational, and if so, the duration of time and intensity of thebacklight. The media player operational parameters 306 can also includea current stored energy state indicating an amount of available usefulenergy that is stored in the internal power supply 302.

The media delivery accessory 102 also includes a processor unit 308coupled to an internal power supply monitor 309 arranged to monitor acharge status of a media delivery accessory internal power supply 310that is used to provide power to the speakers 118. In the describedembodiment, the internal power supply monitor 309 includes a capacitor312 that is coupled to the media delivery accessory internal powersupply 310 in such a way that a capacitor voltage V_(c) across thecapacitor 312 correlates to the charge status of the internal powersupply 310. It should be noted that the internal power supplies 310 and302 are contemplated to be any of a number and type of DC internal powersupplies suitable for portable applications such as a battery (alkaline,nickel metal hydride, etc.) or a small fuel cell.

A detachable power cable 314 provides power to the internal power supply310 from an external power supply when connected to a power port 316. Ina particularly useful embodiment, the power port 316 includes a powercable sensor 318 that reacts to a power cable connect/disconnect eventby sending a power cable status signal 320 to the processor unit 308that signals in the case of a disconnect event that the consumerelectronic product 300 is in a self powered mode (i.e., power issupplied only by the internal power supplies 310 and 302).

During operation of the consumer electronic product 300 when theinternal power supply 310 is providing power to the speakers 118, themonitor 309 tracks the capacitor voltage V_(c) in real time asillustrated in FIG. 4A. In the described embodiment, the voltagefluctuations are used to modify the SPL of the speakers 118 when thecharge status of the internal power supply 310 is in an active region asindicated in FIG. 4B. It should be noted that when the charge statusfalls below a threshold value Q_(th), the charge status is in what isreferred to as a shutdown regime. Furthermore, since an amount of chargeQ_(c) stored in the internal power supply 310 correlates to the energy E(joules) stored in a capacitor having a capacitance C (farads) isrelated to the capacitor voltage V_(c) by equation E=CV₂₄. Therefore, ΔE(and therefore ΔQ_(c)) is directly proportional to ΔV_(c). In theself-powered mode, the internal power supply 310 provides all thenecessary electrical energy to drive the speakers 118. The speakers 118,in turn, mechanically convert this electrical energy to acoustic energythat can be measured as a sound pressure level (SPL) perceived by thehuman ear as a volume level. Therefore, in order to reduce the amount ofcharge drained from the internal power supply 310 and therefore extendthe operation of the consumer electronic product 300, the maximumallowable SPL of the speakers 118 is reduced. In this way, the chargestored in the energy storage device 310 is preserved, prolonging theoperation of the consumer device 300 without noticeably affecting auser's enjoyment of same.

In order to quantify this reduction in SPL, the monitor 309 tracks thecapacitor voltage V_(c) (typically in a range of 200-300 volts) in realtime (as in FIG. 4A) and whenever the tracked capacitor voltage Vc hasan down-going voltage transition 400 that crosses a threshold voltageV_(TH) (about 180-200 volts) and re-crosses the threshold during asubsequent up-going voltage transition, the monitor 309 notifies theprocessor 308 that a volume clipping event has occurred (noted as A, B,and C). This notification is communicated by the monitor 309 to theprocessor 308 by way of a volume clipping signal V_(CL). The processor308 responds to the volume clipping signal V_(CL), by decreasing themaximum available sound pressure level of the speakers 118 by a SPLreduction factor ASPL (see FIG. 5). In this way, the remaining availablestored charge in the internal power supply 310 is preserved resulting ina longer playtime for the consumer electronic product 300 than wouldotherwise be available. In those situations, however, then the trackedcapacitor voltage V_(C) has an down-going voltage transition 400 thatcrosses a threshold voltage V_(TH) and does not subsequently re-crossthe threshold during a subsequent up-going voltage transition, themonitor 309 notifies the processor 308 that a gentle shutdown event hasoccurred (noted as D). The processor 308 then gently shuts down thesystem in order to avoid audio artifacts.

It should be noted, in those situations where a user set output SPL(using a volume control input) is less than the maximum allowable SPL(see FIG. 6), there is no reduction is output SPL (or perceived volume).However, in those cases where the maximum allowable SPL is reduced dueto a clipping event and that clipping event induced reduction in SPLcauses the output SPL to exceed the new maximum allowable SPL, then theuser set output SPL is reduced to a level no greater than the mostrecent maximum allowable SPL. In this case, there remains thepossibility that a user would notice a reduced perceived volume of anyaudio from the speakers 118. However, it is reasonable that the volumereduction would be slight and barely noticed.

As the charge stored in the internal power supply 310 decreases withusage over time, every subsequent volume clipping event causes theprocessor 308 to reduce the maximum allowable SPL by the SPL reductionfactor ASPL. However, at some point (t=t₅ in FIG. 5) down going voltagefluctuations cross a second, lower threshold indicating that theinternal power supply 310 no longer has sufficient stored charge tooperate the media delivery accessory 102 in satisfactory manner (i.e.,the speakers 118 can no longer be adequately driven to produce anacceptable SPL, resulting in unacceptably low perceived volume). At thispoint, the processor 308 executes what is referred to as a gracefulshutdown by sending a muting signal to the output audio processorconcurrently with shutting down power to the remaining components in theconsumer electronic product 300. Such components include any digitalsignal processing circuitry, audio amplifiers, and any other relatedsubsystems.

It should be noted that at any time the power cable 314 is connected tothe external power supply while the media delivery accessory 102 isoperating in the self powered mode, the processor 308 immediatelysignals the media delivery accessory 102 to enter an external powermode. In the external power mode (also referred to as the AC mode), themaximum allowable SPL reverts to the AC mode maximum allowable SPLaffording the user the ability to increase the perceived audio volumeaccordingly. However, it is well to note that this increase in allowableSPL is only a potentiality and does nothing to increase the already setoutput SPL of the consumer electronic product 300 (i.e., the perceivedvolume is unchanged unless user action is taken). Conversely, when thepower cable is disconnected and the media delivery accessory 102 goesfrom the AC mode into the self powered, or DC mode, the maximumallowable SPL is reduced to the DC mode maximum allowable SPL. In thissituation, the processor 308 determines an amount of charge stored inthe internal power supply 310 and based upon that determination sets themaximum SPL level accordingly. For example, if the transition from theAC to DC mode occurs when the internal power supply 310 is fullycharged, then the maximum SPL level is set to SPL_(DCO), whereas if theenergy stored in the internal power supply 310 is less than fullycharged, then the maximum SPL_(DC) level is set to a lesser value, suchas SPL₂₈₃, SPL₂₈₄, and so on.

In some embodiments, the energy provided by the external power supply byway of the cable 314 is used to not only operate the consumer electronicproduct 300, but to recharge (if necessary) the internal power supplies302 and 310. In this case, a transition from DC mode to AC mode and backto DC mode again can result in the processor 308 setting the maximumallowable SPL_(DC) at a higher level than would otherwise be the casewith no recharging.

FIG. 7 illustrates a causal relationship between the period of time ofuseful operation of the consumer electronic product 300 and the actualoutput SPL of the speakers 118. It is not surprising when the actualoutput SPL is reduced (and the charge drain from the internal powersupply 310 is concomitantly reduced), the length of time t₇ that theconsumer electronic product 300 can operate in a satisfactory manner isextended. (This can also be seen in FIG. 6 where the actual SPL is lessthan the DC maximum allowable SPL from t₀ to approximately t₄.

FIG. 8 shows a flowchart detailing a process 800 in accordance with anembodiment of the invention. The process 800 begins at 802 bydetermining if the media player is connected to the media deliveryaccessory. When connected, a determination is made at 804 if the powercable is connected to an external power supply. It should be noted thatthis determination can be accomplished in any number of ways. Forexample, the determination can be performed by physically detecting thecable or electrically sensing an AC input voltage. In the case where thepower cable is connected to the external power supply, then at 806, thenmaximum allowable sound pressure level (SPL) for the speakers is set toAC maximum allowable SPL. It should be noted that a processor iscontinually monitoring for a power cable connect and disconnect eventthat would in turn change the operating mode from externally poweredmode (AC mode) to self powered mode (DC mode) respectively. Returning to804, if the power cable is not connected to the external power supply(DC mode), a maximum allowable sound pressure level (SPL) for thespeakers is set to DC maximum allowable SPL based upon the monitoring ofthe energy output of the stored energy unit.

FIG. 9 shows a flowchart detailing a process 900 in accordance withanother embodiment of the invention. The process 900 begins at 902 bydetermining if the media player is connected to the media deliveryaccessory. When connected, a determination is made at 904 if the powercable is connected to an external power supply. In the case where thepower cable is connected to the external power supply, then at 906, thenmaximum allowable sound pressure level (SPL) for the speakers is set toAC maximum allowable SPL. On the other hand, if the power cable is notconnected to the external power supply (DC mode), then at 908 a maximumallowable sound pressure level (SPL) for the speakers is set to DCmaximum allowable SPL based upon the monitoring of the charge status ofthe stored energy unit. At 910, a charge status of an internal powersupply is monitored and if at 912 the charge status is less than athreshold value, then the consumer electronic product is shutdown at914. On the other hand, if the charge status at 912 is found to begreater than the threshold value then control is passed back to 910.

FIG. 10 shows a process 1000 for monitoring the charge status of theinternal power supply in accordance with an embodiment of the invention.More particularly, the process 1000 represents a particularimplementation of the monitoring operation described above withreference to step 910 in the process 900 shown in FIG. 9. Accordingly,the process 1000 begins at 1002 by coupling a capacitor to the internalpower supply. At 1004, a voltage V_(c) is generated by the capacitorthat is directly related to the charge status of the internal powersupply. At 1006, the capacitor voltage is tracked in real time and at1010 a determination is made whether the tracked voltage is downwardgoing. If the tracked voltage is downward going, a determination is madewhether or not the downward going voltage has crossed a clipping eventthreshold at 1012. If, at 1014, the downward going voltage has crossedthe clipping event threshold but a subsequent upward going voltage (ifany) does not re-cross the clipping event threshold within apredetermined amount of time, then at 1016 the monitor generates ashutdown signal that instructs the processor to carefully control theshutdown of the system in order to avoid undesired audio artifacts.Otherwise, the monitor generates a clipping event signal at 1016. Itshould be noted that the clipping event signal can also be proportionalto an amount of time that the upward going voltage is below thethreshold indicating a weakened state of the internal power supply.

FIG. 11 shows a flowchart detailing a process 1100 for gently shuttingdown the consumer product in accordance with an embodiment of theinvention. At 1102 a determination is made whether or not there is animminent loss of power expected. In the described embodiment, theshutdown signal is used to notify the processor to begin gently shuttingdown the consumer electronic product. Once it has been determined thatloss of power is imminent, then at 1104 the audio amplifier is muted inorder to prevent any audio artifacts (such as a popping sound typicallyheard when sound systems are shut off abruptly). At 1106, a userfeedback is provided indicating that a loss of power is imminent and at1108, if all remaining electronic components are not powered down, thenat 1110, all remaining electronic components are powered down. If, orwhen, all remaining components are powered down, then at 1112, adetermination is made whether or not all residual power used to drivethe gentle shutdown operation has been exhausted. In the describedembodiment, the residual power is derived from the residual chargestored in the capacitor used to monitor the charge status of theinternal power supply. Typically, there is sufficient stored residualcharge to last approximately 5 seconds after the loss of power from theinternal power supply. When all residual power has been exhausted, thenat 1114, all user feedback is stopped. It should be noted, that when theconsumer electronic product is powered up subsequent to the gentleshutdown, the consumer electronic product undergoes a hardware resetoperation.

FIG. 12 shows a schematic diagram of a representative monitoring circuit1200 in accordance with an embodiment of the invention. The monitoringcircuit 1200 includes a capacitor 1202 capable maintaining the capacitorvoltage V_(c) on the order of 300 to 400 volts (equivalent to an energyE related to the capacitor voltage V_(c) as E=CV² discussed above) thatis used to monitor the charge status of the internal power supply. Abattery 1204 (in this case, 9V) provides an input voltage V_(batt) to aboost, or step up, converter 1206 that boosts the input voltage V_(batt)to a range of approximately 300-400 volts that is applied to a firstnode of the capacitor 1202, the second of which is connected to ground.The capacitor voltage V_(c) developed across the capacitor 1202 is usedto monitor the charge status of the internal power supply. A buck (or DCto DC step down) converter 1208 also coupled to the first node of thecapacitor 1202 provides an output voltage V_(out) that is used by aspeaker amplifier (not shown) to drive the speakers. In this way, theenergy used to drive the speakers (which is ultimately provided byenergy stored in the internal power supply) is reflected in the dynamiccharacteristics of the capacitor voltage V_(c) as illustrated above withreference to FIG. 4A. In this way, by monitoring the capacitor voltageV_(c), the charge status (and therefore the capability of the internalpower supply to provide the requisite energy to drive the speakers) canbe inferred without directly monitoring the internal power supplyitself.

Although the media items of emphasis in several of the above embodimentswhere audio items (e.g., audio files or songs), the media items are notlimited to audio items. For example, the media item can alternatively,pertain to recorded discussions and the like.

The invention is preferably implemented by software, but can also beimplemented in hardware or a combination of hardware and software. Theinvention can also be embodied as computer readable code on a computerreadable medium. The computer readable medium is any data storage devicethat can store data which can thereafter be read by a computer system.Examples of the computer readable medium include read-only memory,random-access memory, CD-ROMs, DVDs, magnetic tape, optical data storagedevices, and carrier waves. The computer readable medium can also bedistributed over network-coupled computer systems so that the computerreadable code is stored and executed in a distributed fashion.

The many features and advantages of the present invention are apparentfrom the written description and, thus, it is intended by the appendedclaims to cover all such features and advantages of the invention.Further, since numerous modifications and changes will readily occur tothose skilled in the art, the invention should not be limited to theexact construction and operation as illustrated and described. Hence,all suitable modifications and equivalents may be resorted to as fallingwithin the scope of the invention.

While this invention has been described in terms of a preferredembodiment, there are alterations, permutations, and equivalents thatfall within the scope of this invention. It should also be noted thatthere are many alternative ways of implementing both the process andapparatus of the present invention. It is therefore intended that theinvention be interpreted as including all such alterations,permutations, and equivalents as fall within the true spirit and scopeof the present invention.

What is claimed is:
 1. A method of avoiding generation of audioartifacts while shutting down a consumer electronic product, theconsumer electronic product comprising a plurality of electroniccomponents, the method comprising: determining that a shutdown isimminent, muting an audio amplifier prior to powering down the pluralityof electronic components; providing a user feedback indicating that aloss of power is imminent; powering down the plurality of electroniccomponents in the consumer electronic product; and discontinuing theuser feedback when a residual power is exhausted.
 2. A method as recitedin claim 1, wherein the determining that a shutdown is imminentcomprises: receiving a shutdown signal indicating the imminent loss ofpower.
 3. A method as recited in claim 2, further comprising; receivingresidual power from a stored charge in a capacitor coupled to aninternal power supply used to monitor a charge status of the internalpower supply prior to shutdown.
 4. A method as recited in claim 3,wherein when the stored charge is depleted, then the residual power isexhausted.
 5. The method of claim 1 wherein determining that a shutdownis imminent comprises determining that a voltage across one of theplurality of electronic components remains below a threshold voltageafter a pre-determined length of time.
 6. The method of claim 5 whereindetermining that a voltage across one of the plurality of electroniccomponents remains below a threshold voltage comprises monitoring acharge status of an internal power supply.
 7. The method of claim 1further comprising determining that the residual power is exhausted. 8.The method of claim 7 wherein determining that the residual power isexhausted comprises monitoring a charge status in the internal powersupply.
 9. The method of claim 5 wherein determining that a shutdown isimminent comprises determining that the voltage across one of theplurality of electronic components is below a second threshold voltagelower than the threshold voltage.
 10. The method of claim 6 whereinmonitoring a charge status of an internal power supply comprisescoupling a step up voltage converter and a step down voltage converterto a capacitor, in the internal power supply.
 11. The method of claim 1wherein providing a user feedback indicating that a loss of power isimminent further comprises continuing the user feedback until theresidual power is exhausted.
 12. The method of claim 1 furthercomprising receiving a user feedback through a user input control in theconsumer electronic product.
 13. The method of claim 1 furthercomprising determining if a power cable is connected to an externalpower supply.
 14. A non-transitory computer readable medium comprising acomputer code that when executed by a processor circuit in a consumerelectronic product causes the processor to shut down the consumerelectronic product so as to avoid generation of audio artifacts, theconsumer electronics product comprising a plurality of electroniccomponents, the method comprising: determining when a shutdown isimminent, muting an audio amplifier prior to powering down the pluralityof electronic components; providing a user feedback indicating that aloss of power is imminent; powering down the plurality of electroniccomponents in the consumer electronic product; discontinuing the userfeedback when all residual power is exhausted; and storing the computercode in the non-transitory computer readable medium.
 15. Thenon-transitory computer readable medium as recited in claim 14, whereinthe computer code for determining if a shutdown is imminent comprises:computer code for receiving a shutdown signal indicating the imminentloss of power.
 16. The non-transitory computer readable medium asrecited in claim 15, further comprising; computer code for receivingresidual power from a stored charge in a capacitor coupled to aninternal power supply used to monitor a charge status of the internalpower supply prior to shutdown.
 17. The non-transitory computer readablemedium as recited in claim 16, wherein when the stored charge isdepleted, then the residual power is exhausted.
 18. The computerreadable medium of claim 14 wherein determining that a shutdown isimminent comprises determining that a voltage across one of theplurality of electronic components remains below a threshold voltageafter a pre-determined length of time.
 19. The computer readable mediumof claim 18 wherein determining that a voltage across one of theplurality of electronic components remains below a threshold voltagecomprises monitoring a charge status of an internal power supply. 20.The computer readable medium of claim 14 wherein the method furthercomprises determining that the residual power is exhausted.